Surface Plasmon Interference Lithography Assisted by a Fabry-Perot Cavity Composed of Subwavelength Metal Grating and Thin Metal Film

A surface plasmon interference lithography assisted by a Fabry-Perot （F-P） cavity composed of subwavelength metal gratings and a thin metal fihn is proposed to fabricate high-quality nanopatterns. The calculated results indicate that uniform straight interference fringes with high contrast and high electric-field intensity are formed in the resist under the F-P cavity. The analyses of spatial frequency spectra illuminate the physical mechanism of the formation for the interference fringes. The influence of the F-P cavity spacing is discussed in detail. Moreover, the error analyses reveal that all parameters except the metal grating period in this scheme can bear large tolerances for the device fabrication.

Study on Refraction Index Sensors Using Fiber Grating F-P Cavity

In this paper, the reflective spectra of a refraction index sensor were analyzed based on fiber grating F-P cavity. The sensor was constituted by two identical fiber gratings. Compared with the refraction index sensor using one fiber grating, the fiber grating F-P cavity sensor has narrower resonant peak and it can be used for more accurate measurement. The resonant peaks in the reflective spectra of the sensor are changed with small changes of the refraction index of the measured chemical liquids or cell samples. So it has potential applications in biology and chemistry.

An Ultraviolet Fiber Fabry-Perot Cavity for Florescence Collection of Trapped Ions

We demonstrate a fiber Fabry-Pérot cavity in the ultraviolet range, which covers the florescence wavelength for the 2P to 2S transition of Yb and is designed in the bad cavity limit for florescence collection. Benefiting from both the small cavity mode volume and the large atom dipole, a cavity with moderate finesse and high transmission still supports a good cooperativity, which is made and tested in experiment. Based on the measured experimental parameters, simulation performed on the cavity and ion shows a Purcell factor better than 2.5 and a single-mode fiber collection efficiency over 10%. This technology can support ultra-bright single photon sources based on trapped ions and can provide the possibility to link remote atoms as a quantum network.

Structure Design of Disposable Ocean Temperature Depth Sensing Probe Based on F-P Cavity and FBG

The basic principle of sensing is the combination of F-P cavity interference and fiber grating reflection. A hybrid structure sensor probe has been designed based on the combination of an F-P cavity of liquid-filled thermometer structure, and a fiber grating with an elastic diaphragm, herein F-P cavity is used for temperature sensing, and the fiber grating is used for pressure sensing. By adopting the dual optical path structure, the dual-parameter detection of temperature and depth is realized, which solves the problem of low accuracy caused by the cross response of temperature and pressure of a single sensor device and the calculation of the depth information of the ocean with empirical formulas. Compared with traditional sensors, the sensitivity is effectively improved. Theoretical analysis shows that the sensitivity of the F-P cavity with a thermometer structure filled with kerosene reaches 1.334 nm/?C, and the depth sensitivity of the fiber grating is 284.6 pm/Mpa within the ocean depth range of 0 - 400 m.

Improved Directivity of an OAM Antenna by a Fabry-Perot Cavity: An Experimental Study

The circular phased antenna array is commonly used for generating waves bearing Orbital Angular Momentum (OAM) in the radio frequency band, but it achieves a relatively low directivity. To overcome this drawback, we present here a method to improve the directivity of an OAM circular phased antenna array by embedding it inside a Fabry-Perot cavity. The Fabry-Perot cavity contains three main parts: a partially reflecting surface (PRS), an air cavity and a ground plane. Simulation data show that the directivity of this new OAM antenna achieves an improvement of 8.2 dB over the original array. A prototype is realized and characterized. The simulated and measured characteristics are in good agreement.

基于MOEMS敏感结构的非本征F-P干涉仪式光纤声压传感器

随着声学探测技术的不断进步,对声压传感器提出了高精度、小型化、抗电磁干扰能力强和易批量生产等要求。研制了基于微光电子机械系统(MOEMS)敏感结构的非本征Fabry-Perot(F-P)干涉仪式光纤声压传感器。利用圆片级集成技术实现MOEMS敏感结构与光学腔室的高精度对准,大大提高了传感器的一致性。声压传感器的声学性能测试结果表明,其具有高灵敏度和良好的线性响应度,信噪比达到78.3 dB,实现了对声压信号的优良响应。此外,该传感器既具有光纤传感技术精度高和抗电磁干扰能力强等优点,又具备了微电子机械系统(MEMS)体积小和易批量生产的优势。

基于光纤Fabry-Perot传感器的静冰压力检测方法

针对静冰压力检测需求,提出了一种基于光纤Fabry-Perot传感原理的静冰压力检测方法。其特点是结合精密切割方法,制备了一种单模光纤-毛细玻璃管-单模光纤结构的Fabry-Perot(F-P)传感器,并采用金属管/PDMS(聚二甲基硅氧烷)填充方法对传感器进行了封装。为了提升传感器的抗温度干扰能力,采用了双传感器检测方法。在此基础上,进行了基于光纤F-P传感器的静冰内部应力检测实验,研究了传感器受到冰温压力时的干涉谱峰偏移情况。实验结果表明:在静冰冷冻与融化过程中,传感器干涉光谱的谱峰移动达14 nm。同时双传感器检测方法明显提升了温度抗干扰能力。

Vibration insensitive optical ring cavity

The mounting configuration of an optical ring cavity is optimized for vibration insensitivity by finite element analysis. A minimum response to vertical accelerations is found by simulations made for different supporting positions.

Low insertion loss silicon-based spatial light modulator with high reflective materials outside Fabry–Perot cavity

The extinction ratio and insertion loss of spatial light modulator are subject to the material problem, thus limiting its applications. One reflection-type silicon-based spatial light modulator with high reflective materials outside the Fabry-Perot cavity is demonstrated in this paper. The reflectivity values of the outside-cavity materials with different film layer numbers are simulated. The reflectivity values of 6-pair Ta2O5/SiO2 films at 1550 nm are experimentally verified to be as high as 99.9%. The surfaces of 6-pair Ta2O5/SiO2 films are smooth: their root-mean-square roughness values are as small as 0.53 nm. The insertion loss of the device at 1550 nm is only 1.2 dB. The high extinction ratio of the device at 1550 nm and 11 V is achieved to be 29.7 dB. The spatial light modulator has a high extinction ratio and low insertion loss for applications.

基于可重构PRS的一维电子波束转向Fabry-Perot天线设计

设计了一种具有一维电子波束转向的新型Fabry-Perot(F-P)谐振腔天线。该天线由同轴探针馈电的方形微带贴片天线作为辐射源,并采用加载PIN二极管的可重构部分反射表面(Partially Reflective Surface,PRS)实现波束转向。所设计的可重构PRS由6×6个花瓣型单元组成,并均分为相等的两部分Part 1和Part 2,分别由两个控制信号独立控制,因此可以有选择地调节每部分PIN二极管的开关状态。所设计的天线具有三种不同的辐射模式。测量结果表明,天线主波束能够在+9°、0°、-9°三种离散状态下自由切换。所有状态下重叠的阻抗带宽(|S_(11)|<-10 dB)为5.5%(5.43~5.74 GHz),最大增益达到14.2 dBi。

Dual-band simultaneous lasing in MOFs single crystals with Fabry-Perot microcavities

Multi-band microlasers based on single microcrystalline materials with Fabry-Perot(F-P) cavities are critically and technologically essential. Here, we demonstrate simultaneous dual-band lasing output(615 and 685 nm) in metal-organic frameworks(MOFs) and organic dyes hybrid single crystals, which support F-P resonances. Through a two-step assembly strategy, two different types of cationic pyridinium hemicyanine dye molecules can be encapsulated into the channel pores of anionic bioMOF-1-2 Me successfully. In addition, the employment of the host-guest system significantly increases the dye loading, enhances luminescent efficiency, and diminishes the aggregation-caused quenching(ACQ) effect in the resultant MOFs/dye composites.This finding not only combines the characteristic of MOFs materials with excellent luminescent properties of organic dyes, but also points out a simple and promising strategy to design multi-band microlasers based on F-P mechanism, opening a low-cost avenue for the rational design of miniaturized lasers in the future.

Design of Fiber Magnetic Field Sensor Based on Fiber Bragg Grating Fabry-Perot Cavity Ring-Down Spectroscopy

A novel fiber magnetic sensor based on the fiber Bragg grating Fabry-Perot （FBG-FP） cavity ring-down technique with pulse laser injection is proposed and demonstrated theoretically. A general expression of the intensity of the output electric field is derived, and the effect of the external magnetic field on the ring-down time is discussed. The results show that the output light intensity and the ring-down time of the FBG-FP cavity are in the inverse proportion to the magnitude of the external magnetic field. Our results demonstrate the new concept of the fiber magnetic sensor with the FBG-FP cavity ring-down spectroscopy and the technical feasibility.

Study of the characteristics of concentration sensing based on FBG Fabry-Perot cavity

Fiber Bragg grating Fabry-Perot (FBG F-P) cavity is used as the sensing model to measure the refractive index of the liquid solution. The cladding of the fiber, which is used as the F-P cavity, is etched by HF solution to enhance the sensitivity to the external refractive index. The experimental results show that with the concentration change of the external solution, the effective refractive index of etched fiber will change, thus the spectra of FBG F-P cavity will appear a spilt point. The relationship between the wavelength at spilt point and the effective refractive index of etched fiber is approximately linear, and also periodical. The sensing model is theoretically analyzed based on transfer matrix method, and the corresponding mathematic model is established.

Loss Measurement of High-Finesse Fabry-Perot Cavities

The loss of a high-finesse Fabry-Perot cavity was measured using frequency scan and cavity ring-down techniques.Different transverse modes were examined by sweeping the frequency of the laser across the corresponding resonances.In addition,cavity ring-down technique was used to measure the loss of the Fabry-Perot cavity and a simple model was employed to remove the influence of finite response time of the optical switch and the detection circuit.

Analysis of Focusing Orbital Angular Momentum Wave Using Fabry-Perot Cavity

One of the biggest obstacles to the application of orbital angular momentum(OAM)in the microwave field is its divergence problem.This paper presents a full analysis of generating and focusing OAM waves using original and improved Fabry-Perot(F-P)cavities.Utilizing combination of microstrip antenna and original F-P cavity,the gain of the OAM antenna is enhanced from 4.0 dBi to 9.3 dBi and the corresponding divergence angle is decreased from 41to 24.To further improve the performance of the OAM antenna,the improved F-P cavity is introduced.The simulated results show that the gain is further enhanced to 12.0 dBi and the divergence angle is further decreased to be 15.

THE NEW BEHAVIOR OF BIFURCATION AND CHAOS IN A NONLINEAR FABRY-PEROT CAVITY

Ⅰ. INTRODUCTION In a Fabry-Perot cavity, there exist two electric fields, which propagate in the counter direction and interact with each other via the absorber, so that the theoretical analysis of the Fabry-Perot system is very complicated. On account of this, many authors had focused their attention on the ring cavity, a considerably simple system. It was proposed as a

High-sensitivity refractive index sensors based on Fano resonance in a metal-insulator-metal based arc-shaped resonator coupled with a rectangular stub

A metal-insulator-metal(MIM)-based arc-shaped resonator coupled with a rectangular stub(MARS) structure is proposed. This structure can generate two tunable Fano resonances originating from two different mechanisms. The structure has the advantage of being sensitive to the refractive index, and this feature makes it favorable for application in various microsensors. The relationship between the structural parameters and Fano resonance is researched using the finite element method(FEM) based on the software COMSOL Multiphysics 5.4. The simulation reveals that the sensitivity reaches1900 nm/refractive index unit(RIU), and the figure of merit(FOM) is 23.75.

Theoretical analysis of transmission characteristics for all fiber,multi-cavity Fabry-Perot filters based on fiber Bragg gratings

The characteristics of transmission spectra for the all fiber, multi-cavity Fabry- Perot （FP） configuration based on fiber Bragg gratings （FBG） are theoretically analyzed and modeled. The general transmission matrix function for the structure with any number of cavities is derived, and explicit expression of the power trans- mission coefficient for symmetrical two-cavity FP is presented. The general condi- tions for flat-top single resonant peak at the central wavelength in FBG stop band are derived and verified in the numerical simulation section. The transmission peaks of single-cavity and two-cavity FP structures are compared and discussed, and results show that compared to the single-cavity FP, flatness of the top and steepness at the edge of transmission peak can be improved by introducing one more cavity. The resonant transmission peak properties of two-cavity structure are investigated in detail for various values of cavity length and FBGs with different reflection characteristics, and the design guidelines for transmission-type filters are presented. The results show that the steepness of peak slope can be improved by increase of FBG reflectivities, and these kinds of filters can be used as nar- row-band single-channel selectors and multi-channel wavelength de-multiplexing by properly choosing the length of cavities and reflectivities of FBGs.

A Novel Analytical Approach for Multi-Layer Diaphragm-Based Optical Microelectromechanical-System Pressure Sensors

An optical microelectromechanical-system （MEMS） pressure sensor based on multi-layer circular diaphragm is described and analysed by using the proposed novel analytical approach and the traditional transfer matrix method. The analytical expressions of the deflection of multi-layer diaphragm and absolute optical reflectance are derived respectively. The influence of residual stress on the deflection of diaphragm is also analysed. Simulation results given by the finite element method are consistent with the ones which are analysed by using the analytical approach. The analytical approach will be helpful to design and fabricate the optical MEMS pressure sensors with multi-layer diaphragm based on Fabry-Perot interferometry.

Highly Angular Tolerant Transmission Filters for Narrow-Band Image Sensors

A dielectric transmittance filter composed of subwavelength grating sandwiched between two few-layers distributed Bragg reflectors (DBRs) is proposed with the aim of being compatible with CMOS technology and to be tunable by lithographic means of the grating pattern without the need of thickness changes, in the broad spirit of metamaterials. The DBR mirrors form a Fabry-Perot (FP) cavity whose resonant frequency can be tuned by changing the effective refractive index of the cavity, here, by tailoring the in-plane filling factor of the grating. The structure has been studied and designed by performing numerical simulations using Fourier Modal Method (FMM). This filter proves to have high broad angular tolerance up to ±30˚. This feature is crucial for evaluating the spectral performance of narrow-band filters especially the so-called Ambient light sensors (ALS). By analyzing the transmittance spectral distributions in the band diagram, it is found that the angular tolerance is due to coupling between the FP and the guided mode inside the cavity in analogy to resonances occurring within multimode periodic waveguides in a different context.